Which of the following reagents is most preferred for converting a carboxylic acid into an acid chloride?

Step-by-step solution

The conversion of a carboxylic acid into an acid chloride using thionyl chloride is represented by the equation RCOOH + SOCl₂ RCOCl + SO₂ + HCl Thionyl chloride ( SOCl₂ ) is the most preferred reagent for this reaction. The byproducts formed, sulphur dioxide ( SO₂ ) and hydrogen chloride ( HCl ), are gases that readily escape from the reaction mixture. This leaves behind the acid chloride in a nearly pure state, eliminating the need for complex purification steps.